ajero



Aug. 11, 1959 F. s. AJERO 2,899,089

VEHICLE LIFT GATE ASSEMBLY 2 Sheets-Sheet 1 Filed Nov. 4, -195'? in mii INVENTOR: FORTUNATO 5. AJERO I Q 39 40' BY:

Aug. 11, 1959' F. s. AJERO V 2,899,089

- VEHICLE LIFT GATE ASSEMBLY Filed Nov. 4, 1957 2 Sheets-Sheet 2.

6 IO 5 a 25 v I 7) 26 ==il i I9 45 4 I if 6 2o 24 Hi": "Hi". 24

\N'VENTOR 5/ FORTUNATO S. -AJERO BY:

United States PatentO ,s99,o's VEHICLE LIFT GATE ASSEMBLY Fortunato S. Ajero, Galion, Ohio Application-November 4, 1957, Serial No. 694 428 11 Claims. '(Cl. 214-77) This invention relates tovehicle tailgates; to a tailgate structure: which may be employed as an elevator for vertically moving loads toand from the vehicle body; and more particularly this invention relat'es to a novel tail lift gate construction, including an improved operating mechanism therefor.

Tail lift gates for vehicles, such as trucks and trailers, have been known for some time. On the wliole however, the existing devices are far more complicated in relation to'the work they perform than would seem to be necessary In contrast, the present invention provides a highly simplified and eihcient operating mechanism for tail lift gate assemblies, which mechanism may'be readily provided, with or without the lift. gate; as a packaged unit which may be readily mounted either to existing or new vehicles. The tail lift gate, of course, serves as a vehicle body closure, or it may bearranged as an-elevato'r for raising or lowering loads to and from the vehicle body; and, the operating mechanism provides thetactuating means whereby the gate is positioned upright as a closure or used as an elevator.

The primary object of this'invention accordingly is to provide an improved lift gate operating mechanism includingmeans for moving'thegate vertically or for moving the same to and from an'upright positiommu-tilizing thesam'e powerlmea-nsto accomplish either'lof saidmo'vements Another object of this invention is-to provide a tail lift gate operating mechanismchar'acterized by its' sirnplicity and economy of manufacture, and-which'may'be readily mounted to-new vehicles,ior askan integral unit on existing vehicles without disturbing parts presently mounted thereon;

The foregoing and-otherobjects, advantagesa and features of construction will becotnemore: apparent upon a consideration of the'followingdescription'togethe'r with the accompanying drawings.

In the drawings:

Figure l-is a-more or less diagrammatic sideelevational representation of the'present invention, certaini parts having been omitted for clarity, and showin'g the tail-gate in lowered horiiontal position;

Figure 2 is a view similar to that shownidnFigure 1, but showing the tail lift' gate inraised'horizontalfposition;

Figure 3 isa view similar to that shown in Figuresl and2; showing the lift gate: in upright closed position;

Figure 4 is a rear elevation'al viewtaken imthe'direo tion oi -the arrows 4-4' in Figure 1;

Figure 5 is a plan viewtaken on line-IS 'SL'inFigine 4;

Figure- 6 is aview taken=on* line 6-6' in-Figure4, showing a portion of the supporting niembei's for the operating mechanism; 1 and Figure 7 is a schematic flow diagram iof a hydraulic system which may be employed with therpresent 1nvention.

Lift gates of F the type hereirrdescribed generally are fo u-nd on vehicles such as trucks or trailers; lalthough in many instances th'eymay =b'e u's'ed for raisingnorllowenng 2,899,089 Patented Aug. 11, 1959 2 loads to and from stationary means. Consequently, although the herein inventionis described and illustrated as employed with a truck, it should be understood that this is done by way of example only and is not intended to limit the use of the presentinvention.

Reference is made first to the general environment in which the present lift gate mechanism may be used. Ordinarily, the mechanism will be used at the rear of a vehicle, and, as shown in the drawings, it usually is mounted upon the vehicle frame and below the vehicle body; When used as an elevator for carrying loads to and from a platform or the ground, the lift gate is held ifi horizontal position, as seenin Figure 1. When it is used to load or unload shipments to and from a vehicle body the liftgate is raised to a horizontal position such as that shown in Fi urez. In normally closed position, thelift gate is elevated and positioned upright to provide a closure for the vehicle body, as seen in Figure 3.

only those portions of the vehicle incidental to the present invention are shown in the drawings, including chassisfiame'members 10-16, body cross me mbe'rs 11 and frame members 12 supporting the latter and held on members 10 The vehicle body 13' includes a floor 14 and may or may" not include side walls 15. The rear of the vehicle body generally is open adjacent the floor 14, to receive alift gate 16, which when in elevated position provides an extension for the'body floor 14, and when inu'priglit' position acts'as'a body closure member.

The lift gate operating mechanism generally'is located symmetrically with reference to the lift gate 16 and thevehicle'chassis to assure positiveand balanced operatiori of the gate. In the illustrated embodiment of the invention the parts thus are arranged for symmetrical attachment to the vehicle, there being provided lift linkage and closure linkage for eachend of the gate. However, an arrangement wherein the linkage is attached to the gate substantially around the center thereof also is within the contemplation of the invention; Since the illustrated embodiment of the invention discloses identical actuating linkage for each end of the lift gate 16', only the'linkage for one end will be described, it being understood, of course, that the description is' applicable to both ends.

Support for lift gate 16 is provided by a horiz'ontalshaft 17 suitably supported at its outer end'in a bearing 18 held in a bracket 19' supported by a cross member 20. Lift gate support further includes an arm or support link 21 keyed to shaft 17 adjacent one end thereof, and at its free or' outer end the link 21 has a transverse extension 22 whichis pivotally connected to an end frame member 23 of the lift' gate 16, as shown in Figures 1 and 4 as a pivotalconnection 24 adjacent to what may be referred to as the hinged end of the lift gate 161 At' its inner end shaft 17 is rotatably held-in a support web 25fixed to the vehicle frame. Conveniently, the web also'm'ay provide the support for cross member 20 as we'll as other hereinafter describedparts of'the invention.

Turning of shaft 17 is accomplished by'a'crankarm'26 fixed'non-rotatably thereto and positioned adjacent a web 25. The crank arm 26'has a camsu'rface 2'7 engageable against a roller 28 rotatablyheld on a movable shaft 29. Shaft 29- is'supported-by a secondroller 30 which rotat 'abl-ytravels-in a track provided by a slot 31 in web25;

;in-a--genera1ly horizontal position. As piston rod extension 33 moves: outwardly fromcylinder 35 it carries the roller: 28-on=shaft 29 into engagement with the crank arm 3 cam surface 27, causing the crank arm 26 to turn and rotate its shaft 17. As shaft 17 rotates, its link arm 21 raises lift gate 16.

To assure that lift gate 16 is maintained horizontal as it travels from ground level to a position in the general plane of the vehicle body floor 14, a compression arm 37 is provided. Actually, arm 37 is a jointed arm comprising pivotally connected links or members 38 and 39, the

latter of which is shorter and keyed to a shaft 40 for rotation therewith. The longer link 38 is pivotally connected with the hinged end of lift gate 16 at 41 and below pivotal connection 24.

Shaft 40 at its outer end is rotatably carried in a hearing 42 held in bracket 19, and at its other end is suitably rotatably supported by web 25. Rotation of shaft 40 is achieved by a crank arm 43 which is fixed thereto and carries a cam surface 44 also engageable by roller 28. As roller 28 moves outwardly from cylinder 35 it engages against cam surface 27 to cause shaft 17 to rotate counterclockwise, as viewed in Figures 1 to 3, and raises link 21 and lift gate 16 thereby. In the meanwhile, the smaller link 39 of articulated arm 37 remains stationary while the longer link 38 pivots about the point 45 of arm articulation, which point, during raising of link 21, remains stationary while the outer end of link 38 follows the ris ing lift gate 16. During this time, articulated arm 37, and in particular link 38 thereof, is under compression as it maintains lift gate 16 in a horizontal position. The rotational thrust thus imparted by arms 38 and 39 to shaft 40 is imparted thereby to arm 43, resting against stop 47 (Figs. 1 and 2) which prevents backward rotation of shaft 40 during raising and lowering between the positions of Figs. 1 and 2.

The cam surface 27 of crank arm 26 further is so designed that at substantially the point where lift gate 16 reaches the level of the vehicle floor 14, further movement of roller 28 has no effect on crank arm 26, the cam surface 27 of which is then positioned contiguous and parallel with the path of roller 28.

As roller 28 continues its outward movement from cylinder 35, it next engages the cam surface 44 of crank arm 43. Further travel of roller 28 causes crank arm 43 and shaft 40 to turn clockwise, as viewed in Figures 1 to 3, thereby raising arm 37. Since this further outward movement of roller 28 has no effect on crank arm 27, the pivotal connection of link 21 to lift gate 16 remains stationary. Consequently, as link 37 rises, it causes lift gate 16 to pivot upwardly about its pivotal connection 24 and to an upright position, as best seen in Figure 3.

Roller 28, thus, in effect provides linearly positionable structure which acts as an actuator arranged to operate crank arms 26 and 43. As seen in Figure 1, the actuator roller 28 is engageable with crank arm 26 upon piston rod extension 33 moving outwardly from cylinder 35. As

seen in Figure 2, roller 28 is engageable with crank arm 43, upon rod extension moving in the same direction. And in Figure 3, actuator roller 28 is shown at the limit of its travel, whereat it is positioned against crank arm 43 to hold gate 16 in vertical position while crank arm 26 rests atop roller 28 to maintain or latch the gate in elevated position.

As mentioned hereinbefore, the mechanism for each end of lift gate 16 is identical. As a result, two webs 25, two shafts 17, and two shafts 40 are proviedd. The shafts 17, 17, are arranged in axial alignment, as are the shafts 40, 40. However, shaft 29 extends through both webs 25 to carry rollers 28, 28, which actuate the respective crank arms 26, 26, and 43, 43, on the shafts 17, 17, and 40, 40.

The webs 25, 25, may be attached to the chassis frame members 10 by suitable means such as welding. As a result, the entire lift gate actuating mechanism may be applied to a vehicle as an integral assembly. In carrying this feature out, supporting cross member is fixed to the webs 25, 25, and holds at each of its ends brackets 19,

as seen in Figure 1. wards cylinder 35, the weight of gate 16 causes it to ro- 4 19, which, together with the webs 25, 25, provide support for shafts 17, 17, and 40, 40.

Limiting stops 46 may be provided on the webs 25 for each of the crank arms 26, which stops assure positive stoppage of the rotation of the respective crank arms 26 adjacent thereto once lift gate 16 is raised to the position shown in Figures 2 and 3. Also, stops 47 may be provided on each web 25 to limit the movement of each crank arm 43 when lift gate 16 is in its lowered position, as seen in Figure 1.

As is apparent from the foregoing, each shaft 17, the crank 26 thereon, and the link 21 carried on the shaft, are fixed for common rotation together. Likewise, each shaft 40, its crank arm 43, and the respective links actuated thereby also are arranged together for common rotation.

Referring to Figures 1 and 7, the cylinder 35 has fluid reception ports 48, 49, 'u-t each end thereof, and fluid is carried thereto by respective lines 50, 51, connected to a common control valve 52 to which fluid is supplied by a line 53. By means of valve 52, together with a pump (not shown) fluid may be selectively supplied from a reservoir (also not shown) to either end of cylinder 35 to correspondingly move piston 34. By means of a suitable power take-off the pump may be driven by the vehicle motor.

Briefly, operation is as follows: With the lift gate 16 in lowered position, fluid is supplied to cylinder 35 through its port 48 to drive piston 34 to the right, as viewed in Figure 1. As each roller 28 is carried by piston rod extension 33 outwardly from the cylinder 35,

thereon is resisted by fixed stop 47 (Figs. 2 and 3) engaged by arm 43 and acting through shaft 40 to prevent arm 39 from turning. Once elevation of lift gate 16 ceases, each roller 28 becomes effective to cause rotation of a respective shaft 40, thereby causing the gate to move to the upright position shown in Figure 3.

To lower the lift gate 16, the reverse procedure is followed. That is, fluid is introduced into cylinder 35 through its port 49, thereby driving piston 34 to the left,

As each roller 28 is carried totate about pivot 24 as cam surface 44 bears against the moving roller 28, which action continues utnil arm 38 has moved endwise and caused arms 39 and 43 (fixed with shaft 40) to rotate back until arm 43 encounters its stop 47, when the horizontal position is reached. To

assure positive rotation of gate 16 from its upright position, biasing means may be provided. In the illustrated embodiment of the invention, the biasing means is exemplified by a torsion spring 54 fixed about pivotal connection 41 and anchored between gate end member 23 and link 38 to urge lift gate 16 to rotate clockwise, as viewed in Figure 3.

As lift gate 16 is permitted to move down from its upper horizontal position, its weight causes shaft 17 to rotate clockwise as viewed in Figures 1 to 3, bringing the respective cam surfaces 27 to bear against the retreating rollers 28 until the gate reaches its lowered position as viewed in Figure 1.

It should be understood that each of the cylinder ports '48, 49, is provided with a suitable check valve mechanism, together with means which permits bleeding off of fluid through one cylinder port while fluid is supplied through the other port, as will be apparent to those skilled in the art.

An essential feature of the present invention is that no elaborate latch mechanism need be provided in order to maintain lift gate 16 in the elevated position shown in Figures 2 and 3, even when the gate is carrying heavy 'loads.' This is accomplished by a unique cooperation between the. rollers. 28,, 28, and. the respective cam sunfaces 27, 27,.they engage. Specificallneach. crank arm 26- is so designedv that whenv 'lift. gate 16'v its elevated position, its respective carn surface 27 contiguous with a roller 28 lies parallel with the path of said roller. As a consequence,. not only does. the roller 28 become. ineffective asfar. as turning the crank 27, but the load. on the arm 27 transmitted from gate 16 through link 21 is. applied radially onto the roller 28, or normal to the surface thereof. No component of the load is applied as a turning force. The roller 28 thus effectively acts as. a latch which maintains. lift gate 16 elevated. Further, even after the roller 28 travels outwardly from cylinder 35, the cam surface 27 extends sufli-ciently far to lie parallel with the path of its additional travel, and continues to brought to bear on the roller 28. Thus, even after lift gate 16 is moved to upright position, roller 28' acts asa latch which maintains it in elevated position.

Another feature of the invention is that the entire cross-sectional area of cylinder piston. 34 is utilized ef- 'fectively when raising this gate 16. Put another way, '.the full diameter of piston 34. is available to receive hydraulic pressure when it is desired to raise lift gate 16. For any given size of elevating mechanism, this reduces the size of the cylinder necessary to lift a given load Still another feature of this invention is that the cylinder 35 is mounted stationary. No loads are brought to bear directly upon the cylinder or its piston .rod, but instead the loads are borne by the rollers 28, 28, which travel' in a horizontal path as piston 34 is actuated;

As is apparent from the foregoing description, the same direction of piston 34 movement which raises the gate to the position shown 'in Figure 2 also closes the gate to its upright position'as shown 'in Figure 3. Conseqnently, the same setting of valve 52 which directs fluid'through line 50 to move piston 34 to the right, as viewed in Figure '1, also is used when elevating the lift gate 16 to it'supright position shown in Figure 3. Thus, the'entire movement of "the gatefrom its lowered position to its upright closed position, may 'be-accomplished with a single valve setting. Consequently, the lift gate control mechanism, and in particular valve '52, may be greatly simplified.

it may be desirable to provide some form'of holding means to maintain the lift gate in its upright position. Such means generally take the *form of chains which lhook the gate to the vehicle body. These holding means, of course, form no part of=the present invention which involves raising and lowering the gate as a platform, or moving it to and from a-cl'osure position. However, when held in elevated position, the herein described links 38, 39, do provide means by which the gate may be maintained upright.

Although 'what has been shown and described is a preferred embodiment of the5invention,=i't is to "be under stood that the hereindisclosure is not intended to be exhaustive nor limiting the invention, 'but instead-i's Igiven forthe purpose of ill-ustrat-ion so that the invention may bebetter understood.

Various changes and rearrangements of the details shown and described may be made without departing from the spirit of the invention, the scope of which is defined in the appended claims.

What is claimed is: p

1. Apparatus comprising: a generally flat member; linkage for supporting-said member including a-lift arm pivotally'attachedwith said member at one end',-and link means connected-withsaid member and arrangedwith said lift anm for cooperation-therewith-to maintain-said member substantially horizontal during vertical 'movement thereof; a crank arm; means whereby said crank arm is arranged to rotate said lift arm; linkage actuat- .ing means including movable means arranged to turn .said crank arm, further means arranged for guiding said 6 movable means alongv a. predetermined substantially lidear path power. means connected with said linearly movable means for driving. the same in either direction along said predeterminedipath, whereby upon movement of said linearly movable means in a first direction, said member moves. towards a lowered position, and" move= ment of said linearly movable means in. an opposed d'i-' rectionmovessaidmember towards a predetermined elevated position, said crank arm including. means adapted to ride atop said linearly movable means and out of the path thereof upon said member reaching said predeterrmined elevatedposition, whereby said member is assured- :ly maintained inelevated position.

2. Apparatus for providing a vehicle combination elevator and tail.- gate. assembly, comprising: a generally flatmember;v linkage for supporting said member including at least one lift arm pivotally attached with said member at one end and at its other end mounted for rotation about a. hired point;, link means arranged with said. lift arm for cooperation therewith to maintain said member substantially horizontal during vertical movement thereof;,lift arm actuating means for. effecting vertical movement of said member in horizontal condition and including means operatively connected with said lift arm for applying torque thereto; hydraulic actuated power means for operating the latter means, including a stationary mounted'cylinder, avpiston and rod therein, structure connected with said rod and operative on said latter means, and means for guiding said structure along a substantially. linear path, whereby movement of said structure in a first direction correspondingly elevates said member in horizontal condition towards a predetermined position, and'movement of said structure in an opposed direction correspondingly efiects movement of said member in horizontal condition towards a lowered position; and a. crank arm connected. with said link means, interposed in the path of said structure and engageable thereby, upon said structure moving' in said first. direction and said member reaching said predetermined. position, to actuate said link means, the effective length of" said" link means'being such as to cause swinging of said'memb'er to vertical c'losure'position, said latter means including a second crank arm having a cam surface interposed in the path of said structure and against'which' the same 'bears assaid member moves between said positions, said cam surface being positionable, contiguous withsaid path and still engageab'le with said structure duringmovement of said structure against said" crank arm to maintain said member assuredly at said predetermined elevated position.

3'. Apparatus for providing a combination elevator and tail gate assembly for' a vehicle, comprising: a gate member; lift' arms symmetricallyarranged with respect to saidgate-member for pivotal attachment thereto at 'oneof their respective ends;'each-'lift arm-being mounted at its other end to a shaft for rotation about a fixed pointy link means pivotally'attached to said gate member and cooperable with said lift arms to maintain said gate member horizontal during vertical movement thereof; a crank arm operativel'yassociated-with at least one of" said lift-arms-to-effect turning thereof, a-nactuating member arranged for operative engagement with said cranl arm; means for guiding said actuating member along a subtantially-linear path; power means for mov ing" said actuating-member in either of opposed directions along saidpath; whereby movement of said actuating member in one direction raises-said gate member "towards 'a' predetermined elevated. position and movement 'of said"actuatingmember in-the opposed direction eiiective'ly'moves said gate" member'towards a lowered position; and-a second crank arm positioned for engagement by said actuating member upon said gate member attaining said elevated position and said actuating mem ber moving further in said one direction, said second crank arm being operatively associated with said link means to effect operation thereof'and pivoting of said gate member about its pivotal connections with said lift arms, said further movement of said actuating member having no effect on said lift arms, said crank armincluding a surface interposed in the path of said actuating member during vertical movement of said gate member between said positions, arranged to lie substantially parallel with the path of said actuating member during said further movement thereof, but adapted to continue to bear against said actuating member to assuredly maintain said gate member elevated.

4. Load-unload apparatus for mounting on a road vehicle, comprising an elevator and means for raising and lowering it between lowered and raised positions wherein which intersects the path of the other, means linking the driven member to the elevator to bring the elevator from lowered to raised position responsive to the forward movement of the driven member and to return the elevator from raised to lowered position responsive to the return movement of the driven member, power means for moving the drive member in its forward and return movements to cause the driven member to execute its said movements to raise and lower the elevator, and camming means contained in the driving and driven members and in their guiding means for maintaining driving engagement during the said elevator movement, the camming means moving the driven member substantially out of the path of the drive member as the elevator reaches its said raised position, the camming means then delivering the thrust of the raised elevator through the driven member to the drive member generally at right angles to the portion of the drive-member path the drive member then occupies.

5. Load-unload apparatus according to claim 4, wherein, upon the said elevator being brought into its said raised position, the said camming means maintains a holding engagement between the said members which locks the elevator in raised position in the absence of a return power thrust on the drive member by the said power means.

6. Load-unload apparatus according to claim 4, wherein the said path of the said drive member has a forward section which extends forwardly beyond the position occupied by the drive means when the said elevator has reached its said raised position, the said camming means maintaining a holding engagement between the said members, while the drive means is within the forward section of its path, which locks the elevator in raised position in the absence of a return power thrust on the drive member by the said power means.

7. Load-unload apparatus according to claim 4, wherein the said path of the said drive member is along a straight line, whereby a straight-line piston-cylinder couple may comprise the said power means.

8. Load-unload apparatus according to olairn 7, wherein the said path of the said driven member is along the circumference of a circle along a chord of which the said path. of the said drive member extends, the said driven member having the form of a lever arm pivoted at the center of the circle and extending into the path of the driven member.

9. Load-unload apparatus according to claim 4, wherein the said elevator is a gate-like structure which is horizontally disposed in and between its said lowered and raised positions and is pivotally supported by the said linking means along the side of elevator closest to the vehicle, the said driven member comprising the first of two driven members each mutually engageable with the said drive member, the said path of the said drive memher having an extension'lying forwardly of the position occupied by the drive member when the rising elevator reaches raised position, means for guiding the second driven member for forward and return movement along a path which coincides with the forward extension of the path of the drive member, stop means limiting the return movement of the second driven member, second linking means linking the second driven. member to the elevator to maintain the second driven member at the limit of its return movement and to support the elevator horizontally in and between its lowered and raised positions, movement of the drive means forwardly through the forward extension of its path after the elevator has been brought to its raised position maintaining holding engagement with the first driven means through the said camming means and effecting operating engagement with the second driven member to move it forwardly along its path to tilt the elevator from horizontal to vertical position through-the second linking means.'

l0. Apparatus'for positioning a road-vehicle tail gate which serves also as a load-unload elevator platform between an upright closure position with respect to the vehicle body, an upper horizontal position in cooperative load-unload association with the vehicle body, and a lower horizontal position in cooperative load-unload association with the roadway, comprising a driven reciprocable lift controller and a driven reciprocable tilt controller, a drive link linking the lift controller to the tail. gate to raise and lower it responsive to forward and reverse movement of the lift controller, a tilt-link linking the tilt controller to the tail gate to tilt it between its upper horizontal and its upright positions responsive to forward and reverse movement of the tilt controller, a drive member and power means for moving it forwardly and reversely along a path wherein it operatively engages the driven controllers in succession, forward movement of the drive member first engaging'and moving the lift controller forwardly to lift the gate from its lower to its upper horizontal position, the drive member, during its further forward movement, maintaining holding engagement with the lift controller to hold the gate lifted and alsoengaging and moving the tilt controller forwardly to tilt the gate from its upper horizontal position into its upright closure position, movement of the drive member in its reverse direction first acting through the tilt controller to tilt the gate from its upright position .ino its upper horizontal position while maintaining the References Cited in the file of this patent UNITED STATES PATENTS Penney Dec. 4, 1945 2,469,321 Wood May 3, 1949 2,576,881 Kern Nov. 27, 1951 2,674,386 Larson Apr. 6, 1954 2,683,539 Corley July 13, 1954 Vogel Jan. 21, 1958 

